Commonly, radar targets can be defined on the three RCS frequency regimes based on their body size in wavelengths. These regimes are identifiable for most structures: The Rayleigh region (low-frequency region), the Mie region (Resonant region or medium-frequency), and the optical region (high-frequency region). The RCS’s of insect are little understood, but previous results available suggest that the general scattering characteristics of insects at wavelength of 3.2 cm (X-band) is occurred in high end of the Rayleigh region or in the Resonant region depending on the insect size 17, 31. In such cases, choosing an accurate numerical simulation technique becomes very critical for applications in which the dielectric scattering objects such as insects have a size that is comparable to the probing wavelength. Therefore, the only accurate way to resolve the RCS calculations of these applications is to use the exact methods.